Amplifying horn



Nov. 1, l 932.

, J. J. AUERHAAN AMPLIFYING HORN INVENTOR 1932- J. J. AUERHAAN 1,335,403

AMPLIFYING HORN Original Filed Aug. 23. 1929 2 Sheets-Sheet 2 6 E B/(mEN-roR:

ATTOR Patented Nov. 1 1932 UNITED STATES PATENT OFFICE JOSEPH J. AUERIIAAN, 0F BROOKLYN, YORK, ASSIGNOR TO JOHN H. WORII-IING- TON, OF BROOKLYN, NEW YORK AMPLIFYING HORN a invention relates to horns for amplifyed exponential horns employed for amying such sounds in large or open spaces in theatres, concert halls, or out-door as places.

The object of my invention is to produce an improved method of producing such horns re-by successive layers of the material of which the horn is constructed may be built up evenly to provide uniform density to the walls of the horn, minimum of vibration, strength and rigidity, and whereby all warping, buckling or bulging in the finished product may be obviated.

In carrying my invention into effect I employ a mould. or core upon which the horn is built up. For the large exponential horns of approximately nine, or ten or more feet in l th, and which may be either straight or turned into volute spiral, I prefer to employ a sectional mould or core made of a light metal, such as aluminum, in about eight sections; the large or bell-end section having a flange against which a corresponding flange formed on the built-up horn. The core secti one are preferably hollow and keyed or otherwise detachably secured together on the inside so that they may be removed sectionally when the moulding operation is completed.

ln building up the horn upon the core I may employ various materials such as paper, ch A board. cloth or other woven fabric, such material being employed alone or in combination. I prefer, however, to employ paper or chi p-board of different thicknesses in alternating layers, the layers being composed preferably of 21 or 22 point chip-board alternating with 38 point chip-board, such thicknesses alternatin up to the desired thickness for the walls of the horn and the thinner board preferably constituting the first or inside layer of the horn and the thicker board being preferably employed for the outside layer. When paper or chip-board is em- Original application filed August 23, 1929, Serial No. 387,930. Divided and this application filed September Serial No. 563,048.

ployed for the horn it is preferably prepared for use by first dipping or soaking sheets of suitable size in water and allowing the sheets to drain oil. The wet sheets of one gauge are laid on the core in a single layer while wet and in a pulp-like condition, the core having been previously smeared with a heavy oil or grease. To produce a flat even surface and to work out all creases or wrinkles caused by bending the paper to the curve of the core, and to further pound the paper into a pulp-like condition, it is hammered or pounded by a sort of rolling action with a suitable mallet or pestle-like tool having a relatively large rounded working surface. The first layer of paper is then smeared over with a suitable paste and the second or heavier layer of wet pulp-like paper is applied in the same manner as the first layer. This is continued until the desired thickness is obtained, w

and then the mass is baked, preferably for a period to obtain only partial drying out of the paper, and then the mass is removed from the oven and the core removed. The horn at this stage is allowed to air dry. This manner the outer surface, the inner surface being 1 smooth owing to the smooth hard core surface, and finally the horn is shellacked, painted, or otherwise coated to prevent absorption of moisture, and to impart the desired finish.

Mv invention illustrated in the accompanyin drawings, in which, Figure 1 is a perspective view or" a sectional mould or core tor the large exponential type of horn, the

.e l-end having a laterally project- Figure 2 an enlarged sectional i showing the upper or lower bell flange of t core and the application of the first two U of paper to the core; Figure 3 a. cross section of a corner of the core showing the overla of the paper at the four corners of the horn; Figure 4 a perspective view of a bell-frame which is built into the horn to reinforce the bell of the horn; Figure 5 an enlarged sectional view showing the upper or lower bell flange with he first two layers of paper wrapped around the bell-frame; Figure 6 a view similar to Figure 5 but showing either of the side flanges of the bell-end of the horn and which view illustrates the difference in flare in the side walls as compared to the top and bottom walls illustrated by Figure 5; Figure 7 cross section of a corner of the core and paper layers showing afurther development of the overlap as started in Figure 3; Figure 8 erspective view of the paper horn as built-up on the core and illustrating the stage of production either before or after the core is removed; Figure 9 a perspective View of the horn after it is heat cured, air dried, rubbed down, painted and shellacked, and with the supportingraclrbuilt thereombut before the small or speaker-end is placed in position; Figure 10 a perspective view of the speak rend of the horn; Figure 11 a partial perspective like Figure 9 but showing the speaker-end of the horn in position; Figure 12 a 1 artial side elevation showin! the retaining yoke for the speaker-end of the horn and a ule block mounted on the yoke; Figure 13 a horizontal section on line 13-13 of Figure 12 showing a plan of the yoke and ferrule bloclr ,Figure 14 an enlarged view showing a part of the speaker-end of the horn, part of the yoke, the ferrule block in cross section, the ferrule in the small end of the horn, and the speaker unit mounted on the ferrule; and Figure 15 a perspective view of the complete horn.

Referring to Figure 1 of the drawings, which illustrates the preferred form of core for a large horn having its small end curved back into volute spiral form, it will be noted that the core is made up of a number of sections, and that there may be as many sections as the size and shape of the horn to be produced thereon may dictate. In Figure 1 the core is shown as made of seven sections as indicated at p 1, each section being of gradually i creasing size, and a-large or hell section 2 having a flange 3, about two or three inches in width, extending entirely around the bell-end of the core. The flare of the core at the bell-end is about the same at the top and bottom walls i and 5, but the side walls 6 have a greatly reduced flare as will be more readily seen by a comparison of Figures 5 and 6 which show enlarged sections of bottom wall 5, side wall 6, and bell-flange 3. As above stated the core is preferably made of metal and as light as possible, therefore, it is preferably made of aluminum, and I also prefer to make the core sections hollow. The core sections will be so formed that the joints between sections will be as close and as smooth as possible so that no breaks or ridges will be formed on the interior surface of the builtup horn. These sections will be locked to each other in any suitable manner, but since the core, per se, forms no part of the present invention the details of the'joints and looking means are not illustrated. It will be understood that while I have shown a core which i rectangular in cross section, my method of building up the horn is not limited to the production of that type of born. The horn may be circular or oval or of any other form in cross section, and the mould or core, of course, will havea corresponding shape.

The paper or chip-board sheets may be of any desired or standard stock size, or they may be specially cut to match the taper of the core sides 4-, 5 and 6. In laying the paper on the core, or one layer upon the other, all crosswise oints between sheets extending lengthwise of the horn, if the sheets are not of the full length of the core, will preferably be butt-jointed. I prefer, however, that the layers of paper for each side of the horn, when the horn is rectangular in crosssection, shall be the full length of the horn, to avoid crosswise joints, and in the case of the first two layers 7 and 8, as shown in Figure 2, the s of paper will be longer than the horn core and extend beyond the bell-flange for the purpose hereinafter explained One of the important steps in my method of building up the horn on the core, is to soak the paper or chin-board sheets in water until thoroughly saturated throughout, allowing the water to drain off until the sheets are in a condition to permit handling, and then applying the wet sheets to the horn core.

The first step in the building of the horn upon the core is to coat the outer surface of the core with a thick fluid or slush, preferably oil or grease, The next step is the application of the first layer of paper, chip-board or other fabric 7 which is laid the full length of the core on the oiled or greased surface with a suitable length overhanging the flange 3 as shown in Figure 2. For the first layer I preferably employ chip-board of the thinner stock above mentioned, and after one sheet is spread out over one side of the core, as for instance, on side 6 of th core, see F igure'3, and its longitudinal edges bent over the corner of the core as shown in Figure 3, it is hammered or pounded flat and even as with a mallet or bat or large round-headed pestle like tool which will be manipulated with a rolling action, to causethe paper to conform to the shape of the core and even out all creases and wrinkles. Vhen this sheet is thoroughly evened out, a sheet of the same thickness is laid on the side 4 of'the core, and similarly hammered down with its longitudinal edge overlapping the overlap from the side 6, and the two overlapping edges are hammered down as close and even as pos sible as shown in Figure 3. The same operation is repeated on the other two sides of the core and similar overlaps made at each corner, and with the same overhang of the sheets 7 at the flange 3 as on the side first laid and as shown in Figure 2, and so that all four sides will have the same amount of overhang. The next step is to coat the first layer of wet paper thus laid on the core with a lay of thick paste, by hand or otherwise,

and upon this coating of paste is laid the second layer of paper 8, also with an overhang the flange 3, as shown in Figure 2, and this layer is applied in single sheets on one side of the core at a time, hammered down, and the corners overlapped as shown in Figure 3, in exactly the same manner as with the first layer of paper 7. This layer of paper, however, is of the thicker stock as indicated by the different thicknesses shown in Figures 2 and 3. The next step is to place the re-enforcing frame shown in F igure 4, in position over the first two layers of paper 7 and 8 as indicated in dotted lines in Figure 2, the side of the frame next to sheet 8, or the sheet itself, being coated with paste. This frame is preferably made of wood, the four sides being joined in any suitable manner, d the corners being made square as shown, rou. if desired,and the dimensions ofthe idesb approximately one by two inches. The frame when placed in position is hammered aga nst the paper and flange 3, and then the other sides are coated with paste and the overlapping ends of the four sheets 8 are wrapped around the frame and hammered closely around all corners.

The three exposed sides of the paper cover d frame 9 are now given another coating of paste, and the four sheets 7 are similarly wrapped around the frame and hammered down. This condition of the building up of the horn is shown in Figures 5 and 6, before, however, the other sheets are added.

The layer of paper sheets 8 are now coatec with paste and a third layer, which will be of the same thickness as the first layer, is applied with its edge abutting against the paste coated edge 10 of the paper covered frame 9. These sheets will be applied in all other respects the same as the first layer, with the overlap at the corners of the core, and the entire surface hammered down to even out the surface. This third layer of paper is then coated with paste and the fourth layer of sheets applied, and which. layer will be of the heavier stock, the corners overlapped, and the whole smoothed out by hammering as with the other layers, and the edges abutting against the frame 9. This operation is now repeated with alternate layers of light and heavy paper until the desired thickness of horn is obtained as indicated by the sheets marked 11 in Figures 5, 6 and 7, and each succeeding layer overlapping at the corners as indicated approximately in Figure 7. I

have found in practice that by hammering the edges of sheets 11 close against the frame 9 that the pulp-like paper and paste make a close joint and that perfect adhesion is obtained, but if desired, t 1e angle formed at the frame 9 and layers 11 may be filled by a fillet of paper as indicated by the dotted line 12 in F in res 5 and 6, and which fillet when used will be hammered hard into the recess.

lVhen the final layer of paper is applied, that layer being of the heavier paper stock, the horn core with the built-up paper there on placed in a baking oven. The drying in the oven is discontinued while a slight amount of moisture still remains in the paper, and the core is then removed by unlocking the sections and removing the large or bell section and successively removing each smaller section. Tl .e paper horn is then set out for final air-drying. Owing to the man= nor of applying the wet paper and paste and the hannnering of each successive layer in the building-up process, the paper layers as sumo a dense pulp-like mass, and then with the baking and final slow airdrying I find that there can be no separation between the layers of paper and that warping or bulging after drying is entirely obviated.

After the horn is thoroughly dry, the outside surface is sand-papered to remove any high spots and to give a smooth finish to the surface. This is not necessary for the inside surface of the horn because due to the smooth surface of the core and the hammering down of the paper layers, that surface will come out sufiiciently smooth. This condition of the horn is represented in Figure 8 of the drawings in which 13 indicates the hardened paper mass so intimately hammered together that the several layers of paper, which when applied were so wet that they were more like pulp, now appear one thickness of paper re-enforced at the hell-end with a flange 14 and thus presenting a self sustaining horn structure. b outside surface of the horn is now coated with a paint sizing and when dry is given a finishing coat of paint. The inside surface of the horn is then cleaned of grease in any suitable manner and a coat of shellac applied. 1 find in practice that what" ever ease adheres to the inside surface of the horn is readily absorbed by shellac and that therefore a reliminary cleaning for removing the grease is not necessary. his coating of shellac may be applied by ipping the entire horn into a shellac bath or the interior may be coated and the grease absorbed by flowing the shellac through the horn.

lVhile the horn as thus produced is selfsustaining, it is preferable to mount it on a rack to support it in the position of Figure 8, or at any other desired angle, and for this purpose a rack is built about the horn as indicated in Figure 9. This rack consists of two bottom pieces 15 secured perpendicular to the 'bell-flange lii two oblique bracingpieces 16 extending between the outer ends of the bottom pieces 15 and the upper ends of side flanges 14; a bottom cross-piece 1'7 tying the bottom pieces 15 together; and a central cross-piece 18 secured to the oblique braces 16 and laid against the underside of the horn about midw ay its length. The crosspiece 18 is shorter than the bottom cross-tie 17 so that in securing it to the oblique braces 16 they will be drawn in against the sides of the horn. Fastened to the inner sides of the braces 16 and the middle cross-tie 18 are pieces of felt or other suitable material 19 to cushion the contact between those parts of the frame and horn.

The small or speaker-end 20 of the horn is shown in perspective in Figure 10. This small horn member is made up of thinner paper layers, about sixteen in number, but it is treated in the same manner as the large horn member and built up on a suitable core. The small end of this horn member 20 is preferably finished straight without liare or offset as shown at 2-1, while its larger end is built with a flange or collar 22 adapted to receive the small end 28 of the horn member 13, and the bore of horn member 20 will be such that the diameter at the seat of collar 22 will make a flush joint with the bore at end 23. The joint between the end 23 and collar 22 is made and sealed with glue and an iron filler. Horn member 20 and the curved part 2% of the large horn member form a volute spiral as shown in Figures 11 and 12.

A yoke is built around the spiral part of the horn for protecting the spiral and a support for the speaker unit. This yolie consists of two long arm pieces 25 secured perpendicularly to the top side of the bell-flange lt and placed against opposite sides of the spiral norn section as shown in Figures 12 and 13. Two cross-pieces 26 are laid across arms 25 and secured thereto so as to secure the throat of the horn. Pieces of felt lining 27 are provided on all four sides of the yoke where it is in contact with the horn to cushion the throat of the horn in the yolre. A ferrule block E28 is also secured across the top side of the yolre. This block has a hole drilled through it to receive the end 21 of the horn, and is also recessed as shown at 29, Figure 14, to receive a flanged ferrule 30. The ferrule is glued to the end of the horn and its flange is screwed to the ferrule bloclr. The ferrule has a screw-threaded extension to receive the speaker unit 31. A felt covered wedge 32, Figure 15, is driven between the larger end of the horn member 20 and,

the bell part 13 of the horn body and same is secured in position by a screw or otherwise. This wedge serves to further secure the small end of the horn and at the same time cushionthe contact betw'eenthese parts of the do 1 limit myself herein to any prescribed thickness for the several layers of paper. It will also be understood that the horn may be finished in one section without the use of the small horn section 20, but for practical reasons, especially when a spiral form is employed, I prefer the two section arrangement because it simplifies the building-up process and avoids diiiiculties which would otherwise be encountered in'th-e core construction and withdrawal from the finished horn. It will also be understood that I do not limit myself to the precise arrangement of supporting rack and yoke shown and described. Furthermore, other modifications in details such as the form and material of the bell-frame 14, the manner of finishing the exterior and interior surfaces of the horn, the form and mode of attaching the connection for the speaker I unit, etc may be made without departing from the spirit of my invention.

I do not claim herein the invention involving the amplifying horn or product of the method ierein described since that invention is embodied in my application filed August 23, 1929, Serial No. 387,930, of which this application is a division.

VVhatT claim is:

1. The method of making amplifying horns, which consists in building up a plurality of layers of wet paper on a core, applying paste between the successivelayers of wet paper, pounding each layer of paper when applied, whereby the successive layers are beaten into a pulpdike mass, and subjecting the built-up mass to heat before removing the core.

2. The method of making amplifying horns, which consists in building up a plurality of layers of wet paper on a core, each layer consisting of sheets extending lengthwise on the core with overlapping joints, ap plying paste between the successive layers of wet paper, pounding each layer when applied, whereby the successive layers are beaten into pulp-like mass, and subjecting the built-up mass to heat before removing the core.

3. The method of making amplifying horns, which consists in building up a plurality of layers of wet paper on a core, applying paste between the successive layers of wet paper, pounding each layer of paper wien applied, whereby the successive layers are beaten into a dense mass, subjecting the builtup mass to heat before removing the core, and

then removing the core and air drying the born.

4. The method of making amplifying horns, which consists in building up a plurality of layers of wet paper on a core, each layer consisting of sheets extending lengthwise on the core with overlapping joints, applying paste between the successive layers of we paper, pounding each layer when applied, whereby the successive layers are beaten into a dense mass, subjecting the built-up mass to heat before removing the core, and then removing the core and air-drying the horn.

5. The method of making amplifying horns, which consists in building up a plurality of layers of wet paper on a core, applying a re-enforcing frame at the bell-end of the horn, applying paste between the successive layers of wet paper, pounding each layer of paper when applied, whereby the successive layers are beaten into a dense mass, and subjecting the built-up mass to heat before removing the core.

6. The method of making amplifying horns, which 'onsists in building up a plurality of layers of wet paper on a core, ap plying a re-enforcing frame at the bell-end of the horn, wrapping said layers of paper around said frame, applying paste between he successive layers of wet paper, pounding each layer of paper when applied, whereby the successive le ers ar beaten into a dense mass, and subjectin the built-up masstoheat before removing the core.

7. The method of making amplifying horns, which consists in building up a plurality of layers of wet paper on a core, applying a re-enforcing frame at the bell-end of the horn, wrapping said layers of paper around said frame, appl ing additional layers of w paper, each of said layers abutting the said 1r me, applying paste between the suc essive layers of wet paper, pounding each layer of paper when applied, whereby the successive layers are beaten into a dense mass, and subjecting the built-up mass to heat before removing the core.

8. The method of making amplifying horns, which consists in building up a plurality of layers of wet paper on a core, said layers of paper e:-:tendiug beyond and over hanging the bell-end of the core, applying a re-enforcin frame at the bell-end of the horn, wrapping said overhanging ends of said layers of paper around said frame, applying paste between the successive layers of wet paper, poundng each layer of paper when applied, whereby the successive layers are beaten into a dense mass, and subjecting the built-up mass to heat before removing the core.

9. The method of making amplifying horns, which consists in building up a plurality of layers of wet paper on a core, said layers, of paper extending beyond and overhanging the bell-end of the core, applying a re-enforcing frame at the bell-end of the horn, wrapping said overhanging ends of said layers of paper around said frame, applying additional layers of wet paper, each of said layers abutting the said paper covered frame, applying paste between the successive layers of wet paper, pounding each layer of paper when applied, whereby the successive layers are beaten into a dense mass, and subjecting the built-up mass to heat before removing the core.

10. The method of making amplifying horns, which consists in building up on a core a plurality of layers of wet paper, the successive layers being of different thicknesses, applying paste between the successive layers of wet paper, pounding each layer of paper when applied, whereby the successive layers are beaten into a dense mass, and subjecting the built-up mass to heat before removing the core.

11. The method of making amplifying horns, which consists in building up on a core a plurality of layers of wet paper, the successive layers being of different thicknesses, each layer consisting of sheets extending lengthwise on the core with overlapping joints, applying paste between the successive layers of wet paper, pounding each layer when applied, whereby the successive layers are beaten into a dense mass, and subjecting the built-up mass to heat before removing the core.

12. The method of making amplifying horns, which consists in building up on a core a plurality of layers of wet paper, the successive layers being of different thicknesses, each layer consisting of sheets extending lengthwise on the core with overlapping joints, applying paste between the successive layers of wet paper, pounding each layer when applied, whereby the successive layers are beaten into a dense mass, subjecting the built-up mass to heat before removing the core, and then removing the core and air drying the horn.

13. The method of making amplifying horns, which consists in applying on a core two layers of wet paper of different thicknesses, applying a re-enforcing frame at the bell-end of the horn, wrapping said layers of paper around said frame, applying additional layers of wet paper, each of said layers abutting the said frame, applying paste between the successive layers of wet paper, pounding each layer of paper when applied, whereby the successive layers are beaten into a dense mass, and subjecting the built-up mass to heat before removing the core.

14. The method of making amplifying horns, which consists in applying on a core two layers of wet paper of different thicknesses, applying a re-enforcing frame at the bell-end. of the horn, wrapping said layers of paper around said frame, applying additional layers of wet paper, said layers being successively of different thicknesses and abutting the said frame, applying paste between the successive layers of Wet paper, pounding each layer of paper when applied, whereby the successive layers are beaten into a dense mass, and subjecting the built-up mass to heat before removing the core.

15. The method of: making amplifying horns, which consists in applying on a core two layers of wet paper of different thicknesses, said layers of paper extending beyond and overhanging the bell-end of the core, applying a re-entorcing frame at the bell-end of the horn, wrapping said overhanging ends 7 of said layers of paper around said frame,

applying paste between the successive layers of wet paper, pounding each layer of paper when applied, whereby the successive layers are beaten into a dense mass, and subjecting the built-up mass to heat before removing the core.

16. The method of making amplifying horns, which consists in applying on a core two layers of wet paper of different thicknesses, said layers of paper extending beyond and overhanging the bell-end of the core, ap-

plying a re-enforcing frame at the bell-end of the horn, wrapping said overhanging ends of said layers of paper around said frame, applying additional layers of wet paper, each of said layers abutting the said paper covered frame and being successively of different thicknesses, applying paste between the suc cessive layers of wet pa er, pounding each layer of paper when applied, whereby the successive layers are beaten into a dense mass, and subjecting the built-up mass to heat be fore removing the core.

This specification signed at New York city, in the county and State of New York,

this fourteenth day of September, 1931.

JOSEPH J. AUERHAAN. 

